[单选题]
A solenoid with 500 turns is 0.(gx rdf2)+mtf 10 m long anrg5zz 0zg; mim5u7;y yd carries a current of 4.0 A. What strength of magner;zyy ;zm 0 gm5i5u7zgtic field will it have at its center?
A. $3.1 \; mT$
B. $6.2 \; mT$
C. $13 \; mT$
D. $25 \; mT$
